Railbase core v0.5.10

Core v0.5.10 — guided CLI launcher.

Running the bare railbase binary at a terminal (no subcommand) now opens a small menu — New project / Run the server / Build / All commands — instead of printing all ~28 subcommands. Picking an action runs it (New project → the interactive scaffold wizard; Run → serve; Build → build); "All commands" shows the full CLI, which stays reachable by name as before.

Strict no-op for non-interactive use: scripts, CI, container entrypoints, railbase <cmd>, --help and --version are unchanged (bare + non-TTY still prints help).

Same data-resident plugin model + pinned plugin key as v0.5.9; binaries unsigned (signing deferred).